1. Field of the Invention
The present invention generally relates to capos for stringed, musical instruments.
2. Description of the Prior Art
A capo is a device used by players of stringed, musical instruments. It is comparable to a clamp which may be mounted around the neck of the instrument at any desired position and which presses the strings onto the fingerboard for the purpose of enabling the player to play in a variety of keys while employing the same fingering. The device had previously been referred to as a xe2x80x9ccapodastroxe2x80x9d, and sometimes a xe2x80x9ccapotastoxe2x80x9d, but now is commonly referred to by just the term xe2x80x9ccapoxe2x80x9d.
Over the last two centuries, capos have been designed in hundreds of different ornamental and structural ways, and there are more than one hundred thirty (130) capo patents. A detailed history of the evolution of the capo, with photographs of the various designs, may be viewed at the Sterner Capo Museum website, at http://w 1.865.telia.com/xcx9cu86505074/capomuseum/.
One of simplest and most commonly used capos is referred to as the xe2x80x9cRussell capoxe2x80x9d, named after its inventor, William H. Russell. The Russell capo has an elastic webbing with three or four grommeted holes, and a steel pin with a rubber covering. The player would need two hands to stretch the capo over the neck of the instrument and insert an end of the steel pin into one of the grommeted holes.
In 1965, James Dunlop developed an ingenious variation of the Russell-type capo. The Dunlop xe2x80x9ctoggle capoxe2x80x9d includes a nylon or polypropylene webbing attached at one end to a moveable lever, and a molded body having a series of open notches. The molded body is placed against the strings of the musical instrument, and the lever is received in a selected notch to provide the desired tension to the webbing. The lever is then locked in place. The Dunlop toggle capo still requires two hands for attachment to the musical instrument.
Another capo design is disclosed in U.S. Pat. No. 5,792,969 to Richard Shubb and David Coontz. This capo has a frame with a top arm to contact the strings and a side arm with a jaw member and a lever member both pivotably attached to the side arm. A thumb screw is used to adjust the capo to the proper tension and for fastening it to the neck of the instrument. Again, the Shubb and Coontz capo requires the player to use two hands for proper placement and adjustment.
Other capo designs were made of metal or plastic and had varying features. There are several on the market today with a heavy spring loaded structure that allows the player to install and remove them with one hand. Although convenient to operate, they have several drawbacks. They are physically quite large and obtrusive looking in use on the instruments. They are also uncomfortable to carry around in a pant pocket. An example of a spring loaded capo is disclosed in U.S. Pat. No. Des. 372,259 to H. Milton Kyser. A less ornamental spring xe2x80x9ctriggerxe2x80x9d capo is disclosed in U.S. Pat. No. Des. 378,825 to James A. Dunlop.
One of the major drawbacks of the Kyser capo and Dunlop trigger capo relates to their heavy and non-adjustable spring pressure. In certain capo models, and in certain positions on the musical instrument, the spring pressure will be too great and will depress the strings with more force than is necessary to hold them against the fret without buzzing. This excessive force may change the tuning of the strings, requiring the player to retune as he or she moves the capo to different positions or removes the capo from the musical instrument.
As is evident from the description of the conventional capos, each exhibits at least one disadvantage due to its mechanical structure: it may be large and cumbersome; it may require two hands to attach or reposition on the instrument neck; or it may not provide the proper tension to the strings.
Another drawback of some existing capos relates to its placement on the musical instrument. The profile of a guitar neck, for example, varies with each guitar and may be oddly shaped in cross-section. The neck is tapered and much thinner at the first fret and thicker as you go up the fingerboard toward the guitar body. The capo should be designed to function on a variety of guitars.
Most of the capos mentioned above contact the underside of the neck of the instrument at only one point, usually at its center. With respect to a guitar, for example, the force required to hold all six strings down is applied at this one point. The larger diameter strings need more force than the smaller diameter strings. In almost all cases, with existing capos, it is difficult to properly apply a tension sufficient enough to hold the large diameter strings down without pulling the other strings out of tune.
It is an object of the present invention to provide an improved capo for a stringed, musical instrument which may be easily attached to and adjusted on the musical instrument by the player using one hand.
It is another object of the present invention to provide a capo for a stringed, musical instrument which is relatively small and lightweight, and may be easily carried in the player""s pocket.
It is yet another object of the present invention to provide a capo for a stringed, musical instrument which can apply in fine gradations the proper tension to the strings of the instrument.
It is a further object of the present invention to provide a capo for a stringed, musical instrument which self-adjusts to the shape of the instrument neck wherever it is placed on the neck to provide the proper tension to the strings.
It is still a further object of the present invention to provide a capo for a stringed, musical instrument which is adapted for use on a variety of instruments having necks of different diameters.
It is still another object of the present invention to provide a capo for a stringed, musical instrument which overcomes the inherent disadvantages of conventional capos.
A capo, formed in accordance with one aspect of the present invention, which incorporates some preferred features, includes a fixed arm and a swing arm moveable relative to the fixed arm. The fixed arm and the swing arm are spaced apart from each other to define therebetween an opening for receiving the neck of the stringed, musical instrument. The swing arm has a free end portion and a toothed end portion opposite the free end portion.
The capo further includes a gear assembly having at least one gear rotatably secured to the fixed arm. The gear engages the toothed end portion of the swing arm. When the user of the capo squeezes the two arms together about the neck of the instrument, the swing arm will move relative to the fixed arm, causing the gear to rotate.
The capo further includes a pawl which is pivotably secured to the fixed arm. The pawl engages the gear assembly and prevents the gear from rotating in at least one direction until the pawl is purposely released from engagement by the player.
Using only one hand, the player places the capo onto the neck of the instrument, with the neck between the two arms, and squeezes the arms together. The swing arm engages the back of the neck while the fixed arm applies pressure to the strings and forces the strings against the fingerboard. By squeezing the arms together, the player causes the swing arm to pivot towards the fixed arm, causing the gear to rotate. The pawl preferably allows the gear to rotate in one direction, to tighten the capo on the instrument neck, but not in the other direction which would loosen the capo. To remove the capo, or to reposition it on the instrument neck, the player disengages the pawl from the gear assembly, which allows the arms of the capo to open.
In order to apply a precise tension to the strings, the capo preferably has a gear assembly comprising a pinion gear and ratchet wheel co-axially mounted together and rotatably secured to the fixed arm. The ratchet wheel engages the pawl. The pinion gear has fewer teeth than the ratchet wheel, and engages the toothed end portion of the swing arm.
The toothed end portion of the swing arm is preferably formed as a gear segment whose teeth intermesh with like teeth of the pinion gear. The ratio of the radius of the toothed end portion of the swing arm to the radius of the pinion gear is preferably between about 2:1 and about 5:1 to provide greater rotation of the pinion gear with correspondingly less rotational movement of the toothed end portion about the pivot point of the swing arm. The gearing, along with the greater number of teeth on the ratchet wheel, provides a very fine resolution in adjustable tension that may be applied by the capo to the strings.
Also, in a preferred embodiment, the swing arm includes a concave swivel shoe mounted on its free end portion. The swivel shoe includes two spaced apart bottom pads which engage the back of the instrument neck in two places. The swivel shoe is mounted on a pivot pin or bushing on the swing arm which is received by an elongated opening formed in the shoe. This allows the swivel shoe to pivot and move longitudinally with respect to the swing arm so that, when the player clamps the capo on the instrument neck, it self-adjusts to whatever shape the neck has and thus applies the proper tension to the strings.
These and other objects, features and advantages of this invention will become apparent from the following detailed description of illustrative embodiments thereof, which is to be read in connection with the accompanying drawing.